Following completion of the trial period for inventory reporting and review, annual review of
individual inventories of each Annex I Party became mandatory in 2003 (decision 19/CP.8). The UNFCCC
inventory review guidelines, adopted in 1999 (decision 6/CP.5) and revised
in 2002 (decision 19/CP.8), ensure that the reviews are conducted consistently in a technically sound
manner. Annual review ensures that adequate consideration is given to recalculations and emission
trends over time.

The review of GHG inventories comprises three stages. Each stage complements the previous one, and
ensures that the process as a whole provides a thorough and technical assessment of the inventory and
of conformity with the UNFCCC and IPCC guidelines. Each stage of the review is finalized with a review
report which is published on the secretariat web site (see navigation bar to left).

Initial check: immediate quality assurance check to verify that the inventory
submission is complete and in the correct format. The result is a status report whose main purpose
is to provide a brief check of completeness of the inventory submission, mainly based on the
CRF.

Synthesis and assessment: Part I compiles and compares basic inventory
information, such as emission trends, activity data and implied emission factors, across Parties
and over time. Part II provides a ‘preliminary assessment’ of the inventory of
individual Parties. The identification of potential problems in this assessment is an important
input to the individual review stage.

Individual review: international teams of sectoral inventory experts examine the
data, methodologies and procedures used in preparing the national inventory. Reviews are conducted
as a centralized review, where 5–8 inventories are reviewed by an expert review team (ERT)
convened at the secretariat; a desk review, where 3–5 inventories are reviewed by experts
based in their home countries; or an in-country review, where a single inventory is reviewed by an
ERT in the Party under review. This is the most important and detailed review stage.

Protection of confidential inventory information

At COP 9 by decision 12/CP.9 Parties adopted a code of practice for the treatment of confidential
information in the technical review of greenhouse gas inventories from Parties included in Annex I to
the Convention. In accordance with this decision, the secretariat has developed procedures to
implement the code of practice during the inventory review in 2004 and beyond. These procedures cover
submission, processing and handling by the secretariat of any information designated as confidential
by an Annex I Party, and the granting of access by expert reviewers to this information.

Expert review teams

The annual inventory review process requires the participation of over 120 skilled experts per year.
Members of expert review teams are selected by the secretariat from experts nominated by Parties. The
secretariat selects experts to ensure coverage of all inventory sectors, and to achieve an overall
balance in the participation of experts from Annex and non-Annex I Parties, as well as geographical
balance among them. Two lead reviewers, one each from an Annex I and a non-Annex I Party, guide the
work of the teams.

Participation of experts nominated by Parties helps to ensure that the review results are objective,
credible and recognized by Parties. In addition, it helps build inventory capacity across all
Parties. Reviewed Parties receive technical feedback from other experts that enables them to further
improve their inventories. Likewise, experts who participate in reviews gain knowledge of inventory
practices of other countries, which they can take home and apply to their own inventories.

As of 2004, all members of expert review teams participating in the technical review of greenhouse
gas inventories must sign an agreement for expert review services. The agreement specifies the
responsibilities, expected time commitment, and appropriate conduct for expert review team members,
in particular with respect to the protection of confidential inventory information, as determined by
the COP. Any new review team members must also successfully complete training on how to perform a
review.

Under the UNFCCC review guidelines (decision 13/CP.20), expert review teams (ERTs) for review of GHG
inventories shall include two lead reviewers, one from a non-Annex I Party and one from an Annex I
Party. These lead reviewers have a special role, ensuring that the reviews are performed by each ERT
according to the relevant review guidelines and consistently across Parties. Lead reviewers should
also ensure the quality, objectivity, continuity, comparability and timeliness of reviews.
The COP requested the secretariat to facilitate meetings of lead reviewers for GHG inventories to
facilitate the work of lead reviewers in fulfilling their task to ensure consistency in the reviews
across Parties. Lead reviewers shall also collectively prepare an annual report to the SBSTA,
containing suggestions on how to improve the quality, efficiency and consistency of the reviews. The
secretariat has conducted eleven meetings of inventory lead reviewers. The conclusions of these
meetings are presented through the following links: